This invention relates to an improvement to a combustion burner structure and more particularly to a premix gas burner assembly for use in a metal melting furnace, and which has feed orifice penetrating inspection and cleaning means.
Modern industrial heating processes and especially metal melting furnaces require burners which have a number of characteristics which have heretofore been compromised. It would be advantageous to improve, without detriment to some, all of the following characteristics:
1. easy clearing of the combustion chamber exit in the event of burner blockage by metal from the furnace, PA1 2. dependable and safe flame ignition and supervision, PA1 3. flame stability without excess and erratic noise, PA1 4. efficient and complete combustion of the air/fuel mixture within the combustion chamber, PA1 5. components which do not overheat, deform, or become damaged during extended periods of operation thereby providing long service life with a low degree of maintenance, PA1 6. wide range of turndown capabilities with accurate control of the products of combustion.
Gas burners may be classified into three types, depending on the method of mixing the gaseous fuel and air.
The simplest arrangement, often called a throat-mix burner, consists of admitting the gas and air into the combustion chamber through separate ports, usually adjacent to each other, and allowing the two gasses to mix and burn in the furnace. This method of burning gas gives large, relatively slow-moving flames and has been widely used in firing open hearth steel furnaces.
A second type of mixing is found in the inspirator type of burner wherein the fuel gas is delivered to the burner under pressure and is discharged from a nozzle or jet in such a way that its momentum is used in mixing the gas with indrawn air.
The third type of burner involves premixing all or part of the air with the gas prior to delivery to the burner. With this arrangement the burner itself may be a relatively simple nozzle designed to deliver the combustible mixture without backfire or flame blowoff. A variety of arrangements are used for premixing and are well known in the art.
With any of these types of burners, the rate of gaseous combustion is markedly increased at hot surfaces. This effect is utilized in tunnel-port burners, in which the burner port or combustion chamber is made from a highly refractory tile and is so arranged that the tile port is heated to incandescence. Under some circumstances, however, this arrangement is disadvantageous as it produces local overheating and rapid erosion of the refractories.
Refractory-tunnel type burners are generally known in the art for use when the fuel and air are mixed within the burner itself. However in order to further accelerate the combustion process and provide high temperatures, it is often desirable to also use a premixture of fuel and air. The resulting severe service conditions leads to certain difficulties in obtaining the above-mentioned desired characteristics.
The above and other characteristics, advantages, and objects are achieved through the present invention as will be readily apparent from the following description.